Sen. Tom Coburn (R., Okla.) told reporters Tuesday he is “discouraged” by the state of the ‘Gang of Six’ negotiations on deficit reduction and said a final deal was unlikely because members are “just too far apart on basic issues.”As a result, he will “take a break” from the negotiations, his office confirms.

“[Dr. Coburn] is disappointed the group has not been able to bridge the gap between what needs to happen and what senators will support,” writes spokesman John Hart. “He still hopes the Senate will, on a bipartisan basis, pass a long-term deficit reduction package this year. He looks forward to working with anyone who is interested in putting forward a plan that is specific, balanced and comprehensive.”

The group was scheduled to meet at 2:30 p.m. today. Coburn showed up briefly to inform the other members of his decision.

The relevance of the ‘Gang’ has been in doubt of late as Vice President Joe Biden convened a separate commission on deficit reduction and Senate Minority Leader Mitch McConnell (R., Ky.) has indicated that the new Biden group held the best opportunity for lawmakers to reach a compromise.

When asked (earlier in the day), other ‘Gang’ members said that they remain somewhat optimistic. Sen. Saxby Chambliss (R., Ga.) said the group was going to “keep working until we come to some solution,” adding “when you get down to the few issues that are really the game-changers, that’s when it gets tough.”

Sen. Mike Crapo (R., Idaho) said he thought a deal could happen but there’s no pressing deadline and no reason to try and attach the Gang’s proposal to a vote on the debt limit.

UPDATE: The sticking point here appears to be “mandatory spending,” i.e., entitlement reform. Coburn reportedly said there is a chance that talks could resume in the future is Democrats are willing to budge on entitlements:

“We can’t bridge the gulf of where we need to go on mandatory spending,” Corburn said Tuesday afternoon. “I don’t see that there’s going to be any fruition in continuing them at this time.”

Coburn has insisted for weeks that Social Security reform, including cutting benefits, would have to be part of any Gang of Six deal. But Democrats such as Sen. Kent Conrad (D-N.D.) said they wanted to deal with Social Security reform separately, not as part of a broad deficit reduction package.

UPDATE II: In a response to this development, Sen. Jeff Sessions (R., Ala.), ranking member on the Senate Budget Committee, calls on Chairman Conrad to “end the budget blockade” in the Senate:

“The news that the Gang of Six has reached an impasse only further underscores that the Democrat-led Senate cannot continue to stonewall the budget process and block a budget from being brought forward in committee,” Sessions said in a statement. “The American people deserve to see an honest plan, on paper, that they and their representatives can evaluate. It’s time to bring this process into the light of day.”

“748 days have gone by since the Democrat Senate has passed a budget. In that time, we accumulated $3.2 trillion in gross debt as we head nearer a fiscal crisis. The Republican House has put forward a plan. The Democrats campaigned for control of this chamber. They asked for the job. Let’s see their budget.”

UPDATE III: Talking Points Memo is reporting that Coburn’s decision stems from the group’s rejection of his proposal to “cut Medicare”:

A source with knowledge of the negotiations says Coburn ultimately broke ranks after members of the group rejected his proposal to introduce a global cap on Medicare spending that would have cut $150 billion from current beneficiaries.

“The issue we have now is, over the last couple weeks Coburn has been slow walking this and it’s become clear that he’s not been negotiating in good faith,” the source said. “He came yesterday with demands that we make immmedate and deep cuts to current Medicare beneficiaries.”

An awfully convenient narrative for Democrats — e.g., “Gang talks fail as Democrats valiantly defend seniors” — not to mention a highly unusual leak (and almost certainty retaliatory in nature) from a group that has maintained a vice-like secrecy in regard to the negotiations. It makes you wonder how serious Democrats are about actually reaching a bipartisan compromise, or if they would be far more content with an failed outcome that suits their political goals heading into 2012.

Coburn spokesman John Hart tells NRO in response: “Democrats and Republicans would be better off focusing on the hard work of deficit reduction instead of speculating about the reasons for an impasse.”

UPDATE IV: Sen. Saxby Chambliss (R., Ga.) tells reporters that without Coburn, ‘Gang’ talks will be suspended indefinitely. In other words, there will be no ‘Gang of Five.’ Chambliss said he regrets Coburn’s decision to drop out, adding that he was “disappointed” that negotiations have failed to yield a consensus by now. “We’ll continue to get together,” he said. “There are still ideas, but it’s not going to be a proposal by five…I want Tom Coburn to be a part of this.”

“The debt is still $14 trillion,” Chambliss continued. “It’s got to be solved and the only way it’s going to be solved is in a bipartisan way.”

Asked what the remaining five members could do to convince Coburn to rejoin, Chambliss shrugged and said he didn’t know.